1. Field of the Invention
The present invention relates to optical switches and optical switch devices having the same, and more particularly, to an optical switch for use with bi-stable mechanisms in conjunction with electro-thermal actuators, and an optical switch device equipped with the optical switch and configured to integrate the optical switch with variable optical attenuators.
2. Description of Related Art
Optical communication products have become mainstream due to the ever-growing demand for faster data transmission capability. Various optical communication components, such as optical fibers, optical waveguides, optical switches (OS), and variable optical attenuators (VOA), are widely used.
Optical fiber has the advantages of high transmission speed, low noise, light weightness and secure privacy and thus has become an indispensable transmission medium for modern communication networks. Optical switches play a key role in the optical switching of light signals in optical communication networks because they can selectively switch signals from an input end to a specific output end of an optical fiber network. Optical attenuators adjust the intensity of optical signals and are effective in measuring indices of optical fiber systems, attenuating signals in short distance communications systems, and testing systems. Currently there are many different techniques available for optical fibers, optical switches and optical attenuators, such as, the thermo-optics techniques, the liquid-crystal technique and Micro-Electro-Mechanical Systems (MEMS).
Referring to FIG. 1A through FIG. 1B, the prior art discloses a MEMS-based cross-bar-type optical switch comprising four optical pathways arranged cruciformly. As shown in FIG. 1A, with a mirror 10 being at a first position 15 (out of the way of the paths of the optical signals), an optical signal input by a first optical input pathway 11 enters a first optical output pathway 13, and an optical signal input by a second optical input pathway 14 enters a second optical output pathway 12. As shown in FIG. 1B, the mirror 10 moves from the first position 15 to a second position (in the way of the paths of the optical signals) to thereby divert the optical signal input by the first optical input pathway 11 to the second optical output pathway 12 and divert the optical signal input by the second optical input pathway 14 to the first optical output pathway 13. However, to prevent optical signals from deviating from the optical pathways, the mirror 10 needs to be double-sided and of a limited thickness. Moreover, extra energy, such as electrostatic energy, is required for keeping the mirror 10 at the first position 15 or the second position.
Regarding optical communication devices, “attenuation-controllable micromachined 2×2 optical switches using 45-deg micromirrors” was proposed by Kwon et al. in 2006; however, the technique is known to cause relatively great optical energy loss since it requires two sets of mirrors in order to reflect input optical signals to an output end. Subsequently in 2008, Chen et al. disclosed a “novel multifunctional device for optical power splitting, switching, and attenuating,” comprising a movable cantilever and a triangular reflective mirror configured to function as an optical splitter and perform optical path switching and optical attenuation by moving or twisting the cantilever. However, with the main application limited to optical switching and adjustment of 1×2 optical pathways and with a difficult fabrication process, the device is less than optimal.
The application of optical fiber technologies is indispensable to optical fiber communication networks, data transmission and cable TV transmission. Consequently, miniaturization, enhancement of optical signal switching speed, and reduction of loss of optical signal energy are the main areas of challenge and the requirements to be met and improved.